Entangled nonwoven fabrics have been well known for many years, and have been used in a variety of products such as aprons, towels, wipes, and facing layers for disposable absorbent articles, such as sanitary napkins and diapers. Such fabrics are typically formed by subjection of a loose array of fibers on a foraminous screen to high pressure liquid jets to displace and entangle fibers in relatively densely entangled areas which are interconnected by less dense fiber bands or bundles. A method and apparatus for forming such an entangled nonwoven fabric is disclosed in detail in Evans U.S Pat. No. 3,485,706. Such fabrics rely for strength on interfiber frictional engagement, and when increased fabric strength is required, an additive adhesive has been used.
The prior art is also replete with examples of fabrics formed of thermoplastic fibers, such as polyethylene and polypropylene, which are heat fused to another.
Prior to the present invention it has also been known to secure plural fabric layers, including layers formed of thermoplastic and non-thermoplastic fibers, to one another to form a laminated structure and adhesive binders have typically been used to join the layers together. Fibrous layers have also been heat laminated with a thermoplastic scrim. In addition, unentangled fibrous layers containing thermoplastic binder material or binder fibers at least at one surface thereof, have been heat laminated to films or other fabric layers. However, due to the lack of entangling, these fabrics do not achieve the fabric strength and resistance to delamination of the laminates of the present invention.
It has also been known in the past to form fabrics of conjugate or bicomponent fibers. Such fibers are typically constructed of an outer component having a melting point lower than the melting point of the inner component thereof, so that upon heating the outer component will melt and upon subsequent cooling will solidify and act as a binder to give the resulting fabric strength and integrity. Fabrics formed of bicomponent fibers are disclosed in Davies U.S. Pat. No. 3,511,747 and Davies et al. U.S. Pat. No. 3,595,731.
Several thin absorbent panty liner products are now on the market which protect the wearer's undergarment both during intramenstrual use and in conjunction with other catamenial devices, during menstrual use. Such products are intended to provide the user with protection from the staining of undergarments, and particularly during non-menstruating days. These products generally are designed to be worn in the crotch portion of an undergarment and comprise a body facing side which is pervious to body fluids, an absorbent body which is capable of absorbing and retaining quantities of body fluid, and a fluid impermeable backing on the garment facing side of the product for preventing the fluid absorbed and retained from "striking through" onto the crotch surface of the undergarment. Generally, these products have been provided with a layer of pressure-sensitive adhesive adhering the product to the crotch portion of the garment. The layers of currently available panty liner products are primarily retained in assembled relationship with one another by the use of an additive adhesive.
It would be desirable to produce a laminated fabric structure without the use of an extraneous adhesive securing means, particularly in a product such as a panty liner.